import java.io.File;
import java.io.IOException;
import java.util.*;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.*;
/**
 * Created by ScorpionOrange on 2016/11/13.
 */
public class FutureTest {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        System.out.print("Enter base directory (e.g. /usr/local/jdk5.0/src): ");
        String directory = in.nextLine();
        System.out.print("Enter keyword (e.g. volatile): ");
        String keyword = in.nextLine();

        MatchCounter counter = new MatchCounter(new File(directory), keyword);
        FutureTask<Integer> task = new FutureTask<>(counter);
        Thread t = new Thread(task);
        t.start();
        try{
            System.out.println(task.get() + " matching files.");
        }
        catch (ExecutionException e){
            e.printStackTrace();
        }
        catch (InterruptedException e){}
    }
}

/**
 * This task counts the files in a directory and its subdirectories that contain a given keyword.
 */
class MatchCounter implements Callable<Integer>{
    private File directory;
    private String keyword;
    private int count;

    /**
     * Constructs a MatchCounter.
     * @param directory the directory in which to start the search
     * @param keyword the keyword to look for
     */
    public MatchCounter(File directory, String keyword){
        this.directory = directory;
        this.keyword = keyword;
    }

    public Integer call(){
        count = 0;
        try{
            File[] files = directory.listFiles();
            List<Future<Integer>> results = new ArrayList<>();

            for(File file : files){
                if(file.isDirectory()){
                    MatchCounter counter = new MatchCounter(file, keyword);
                    FutureTask<Integer> task = new FutureTask<Integer>(counter);
                    results.add(task);
                    Thread t = new Thread(task);
                    t.start();
                }
                else {
                    if(search(file)) count++;
                }
            }
            for(Future<Integer> result : results){
                try{
                    count = count + result.get();
                }
                catch (ExecutionException e){
                    e.printStackTrace();
                }
            }
        }
        catch (InterruptedException e){}

        return count;
    }

    /**
     * Searches a file for a given keyword.
     * @param file the file to search
     * @return true if the keyword is contained in the file
     */
    public boolean search(File file){
        try{
            try(Scanner in = new Scanner(file)){
                boolean found = false;
                while (!found && in.hasNextLine()){
                    String line = in.nextLine();
                    if(line.contains(keyword)){
                        found = true;
                    }
                }
                return found;
            }
        }
        catch (IOException e){
            return false;
        }
    }
}